In the medical field, it is a very common procedure, and often very necessary, to conduct a bleeding time test which measures the time required for the cessation of bleeding following a skin incision. This test is medically important because extended or prolonged bleeding time can be associated with, for example, a lack of or a great excess of platelets, abnormality of platelet function, coating of platelets by specific proteins or foreign materials or the action of certain drugs; e.g., aspirin.
Although the bleeding time test procedure was first described approximately ninety years ago, it did not receive general acceptance until the 1940's at which time the test's sensitivity was increased by making a skin incision on the forearm of the patient while maintaining a blood pressure cuff inflation to maintain venostasis at a standardized level. Using this procedure, a technologist simultaneously starts a stopwatch while making the incision. The emerging blood is then gently blotted every thirty seconds. The cessation of bleeding is defined as the time at which the blotting paper is no longer stained by the emerging blood. This amount of time is generally recorded to the nearest half minute.
Disposable bleeding time devices were first introduced in 1978 to facilitate automation and convenience. These devices improved the acceptance of the test by both the patient and the operator. However, the results were still subject to a variety of technical variables. Additionally, these devices were significantly more expensive than previous methods. This hindered the acceptance of such devices in many countries around the world. Importantly, different disposable devices evolved over time which were functionally quite dissimilar so that the results were not comparable. Thus, standardization remained an elusive goal in bleeding time testing.
An important bleeding time testing device is known as the TRIPLETT (TM) bleeding time testing device. This was named after the noted physician in blood coagulation and hematopathology, Dr. Douglas Triplett. This device is presently manufactured and sold by Helena Laboratories of Beaumont, Tex. This device met the goal of global standardization in bleeding time testing and utilizes advanced technology at a universally affordable price. This was a product that provided a new level of value to automated, disposable bleeding time devices. This TRIPLETT (TM) bleeding time testing device was designed to be user and patient friendly, virtually painless, and to mimic the incision motion of the original bleeding time method. The device makes a standardized surgical incision one millimeter deep by five millimeters long for accurate sensitive bleeding time testing. The blade automatically retracts after incisions so as to ensure safety. The device includes a large contact surface that distributes the downward force over a wider area of skin so as to reduce the potential for deep non-standardized cuts. This device is presently subject to patent protection under U.S. Pat. Nos. 5,662,672 and 5,733,300.
Various other U.S. patents have issued relating to such bleeding time testing devices. For example, U.S. Pat. No. 4,064,871, issued on Dec. 27, 1977 to W. J. Reno, teaches a bleeding time testing device that includes a housing having a surface with a slot defining a longitudinal opening into the housing. A blade is mounted within the housing for movement of the blade tip through and along the slot. Biasing springs are provided within the housing to urge the blade through the slot a predetermined distance and along the slot for a predetermined length to control the depth and length of an incision produced with the device. A trigger is provided to initiate movement of the blade along with a safety pin to prevent the inadvertent activation of the device.
U.S. Pat. No. 4,628,929, issued on Dec. 16, 1986 to Intengan et al., describes another type of retractable bleeding time testing device. This device includes a housing, a hammer mechanism pivotally positioned within the housing and having a cam surface, and a self-retracting shuttle supported within the housing and including a cam follower surface. The shuttle is operative to travel in a vertical direction by the movement of the cam surface along the cam follower surface and the force exerted on the shuttle by a first spring extending from the shuttle. A cutting blade is secured to the shuttle and is operative to move out of the housing to make the incision and then to self-retract into the housing. A second spring is operative to exert a force on the hammer to cause it to move along the cam follower surface and to cause the shuttle to travel downwardly thus causing the blade to travel out of the housing to make the incision. The second spring is also operative to move into a locked position to secure the blade within the housing after the blade has retracted back into the housing.
U.S. Pat. No. 5,031,619, issued on Jul. 16, 1991, to F. Pompei, describes a method for determining bleeding time which includes a cutting assembly and a member for providing a compensation factor as a function of the temperature of the patient. The cutting assembly provides an incision of predetermined dimensions for external bleeding therethrough. The compensation member measures temperature of the patient throughout the period of external bleeding and provides a compensation factor as a function of the sensed temperature.
One of the problems associated with the use of the TRIPLETT (TM) device is that the force applied to actuate the device is off-center from the location at which the blade emerges from the cutting surface. As such, variations of pressures applied to the device can occur. As a result, the bleeding time testing can have a lack of consistent testing. Angular deflections of the cutting surface can also occur by the off-center application of pressure to the actuator of such cutting device. As such, a need has developed for a device for actuating such bleeding time testing devices such that the pressure of actuation will be directly above the location of the incision.
It is an object of the present invention to provide an actuator for a bleeding time testing device which minimizes the variations between operators and the techniques used.
It is another object of the present invention to provide a bleeding time testing device which provides more consistent cutting action.
It is another object of the present invention to provide an actuator for a bleeding time testing device which removes any pressure variations during the incision process.
It is another object of the present invention to provide an actuator for a bleeding time testing device that has a tactile feedback to notify the operator when the actuation has occurred.
It is a further object of the present invention to provide an actuator for a bleeding time testing device which will remain locked down after the actuation so as to assure that the device cannot be reused.
It is a further object of the present invention to provide an actuator for a bleeding time testing device which prevents accidental premature actuation.
It is still a further object of the present invention to provide an actuator for a bleeding time testing device which allows different pressures to be applied to the actuator button by changing the actuator spring.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification.